髄外性胃形質細胞腫の1例

Early-stage Extramedullary Gastric Plasmacytoma, Report of a Case

要旨●患者は60歳代，男性．近医の上部消化管内視鏡検査で病変を指摘されたため，当科に紹介となった．胃体下部小彎に境界やや不明瞭な10mm大の白色扁平隆起を認めた．NBI併用拡大内視鏡検査では病変部のwhite zoneは乳頭・顆粒状構造を呈し，異型に乏しい微小血管の増生を認め，EUSでは第2層の肥厚を呈していた．確定診断を目的にESDを行った結果，病理組織学的には粘膜固有層内に形質細胞がびまん性に増生し，免疫組織化学的にはIgA，κ鎖の単クローン増殖を来しており，髄外性胃形質細胞腫と診断した．H. pylori陽性であり，除菌治療後経過観察中である．

　A 6-year-old man underwent upper gastrointestinal tract endoscopy at a nearby hospital and was referred to our department after a lesion was detected. A poorly-marginated white flat elevation, with a diameter of 10mm, was detected at the lesser curvature of the lower body of the stomach. Magnifying endoscopy with narrow band imaging showed the white zone of the lesion with a papillary and granular structure and atypical microvascular proliferation, whereas endoscopic ultrasound indicated thickness in the second layer. To make a definitive diagnosis, endoscopic submucosal dissection was performed. Histopathological examination revealed diffuse plasma cell proliferation in the lamina propria, whereas immunohistological examination showed monoclonal proliferation of immunoglobulin A and the κ-chain. Based on these findings, he was diagnosed with early-stage extramedullary gastric plasmacytoma. Moreover, a positive result was obtained on Helicobacter pylori testing, and eradication therapy was performed. His clinical course is currently being monitored.